diff --git a/nearby/framework/java/android/nearby/NearbyManager.java b/nearby/framework/java/android/nearby/NearbyManager.java
index a28bc6d..106c290 100644
--- a/nearby/framework/java/android/nearby/NearbyManager.java
+++ b/nearby/framework/java/android/nearby/NearbyManager.java
@@ -208,6 +208,9 @@
                     transport.unregister();
                     mService.unregisterScanListener(transport, mContext.getPackageName(),
                             mContext.getAttributionTag());
+                } else {
+                    Log.e(TAG, "Cannot stop scan with this callback "
+                            + "because it is never registered.");
                 }
             }
         } catch (RemoteException e) {
@@ -264,6 +267,9 @@
                     transport.unregister();
                     mService.stopBroadcast(transport, mContext.getPackageName(),
                             mContext.getAttributionTag());
+                } else {
+                    Log.e(TAG, "Cannot stop broadcast with this callback "
+                            + "because it is never registered.");
                 }
             }
         } catch (RemoteException e) {